Former Defense Secretary Robert Gates’s new memoir hasn’t been a welcome development for Hillary Clinton. In one of the book’s most quoted passages, Gates writes that he witnessed Clinton make a startling confession to Barack Obama: she had opposed George W. Bush‘s last-ditch effort to salvage the Iraq war, the 2007 troop “surge,” because the politics of the 2008 Democratic primaries demanded it.

Clinton’s critics were quick to celebrate the new evidence of the former Secretary of State’s expedience. Clinton, hissed a statement from the conservative Stop Hillary PAC, “will do anything, including mislead the country by putting her political ambitions ahead of the safety of Americans at home and abroad.”

Whatever the truth of that surge anecdote—Clinton’s camp won’t comment on it—the larger truth is impossible to deny. Clinton has demonstrated a well-documented willingness to use American military power overseas. Gates’ book is just the latest evidence, along with previous reporting and original interviews with current and former Obama officials, of the strikingly hawkish voice Clinton offered during Obama Situation Room debates.

As Secretary of State, Clinton backed a bold escalation of the Afghanistan war. She pressed Obama to arm the Syrian rebels, and later endorsed air strikes against the Assad regime. She backed intervention in Libya, and her State Department helped enable Obama’s expansion of lethal drone strikes. In fact, Clinton may have been the administration’s most reliable advocate for military action. On at least three crucial issues—Afghanistan, Libya, and the bin Laden raid—Clinton took a more aggressive line than Gates, a Bush-appointed Republican.

Former administration officials also tell TIME that Clinton was an advocate for maintaining a residual troop force after the U.S. withdrawal from Iraq—an issue of renewed interest given al Qaeda’s resurgence there. They also describe her as skeptical of diplomacy with Iran, and firmly opposed to talk of a “containment” policy that would be an alternative to military action should negotiations with Tehran fail.

Recent comparisons of Secretary of State John Kerry’s frenetic globe-trotting to Clinton’s arguably modest diplomatic achievements have tended to overlook this less visible aspect of her tenure. But no assessment of her time in Obama’s administration would be complete without noting the way Clinton hewed to the liberal hawk philosophy she adopted during her husband’s presidency in the 1990s, and which contributed, less happily, to her 2002 vote to authorize force against Iraq. “The Democratic party has two wings—a pacifist wing and a Scoop Jackson wing. And I think she is clearly in the Scoop Jackson wing,” says former Democratic Congresswoman Jane Harman, now director of the Wilson Center. (Jackson, a Cold War-era Democratic Senator from Washington state, mixed progressive domestic politics with staunch anti-communism, support for a strong military, and backing for the Vietnam War.)

Clinton’s allies resist the word “hawk,” and say a focus on military power doesn’t do justice to her fuller record. “You can’t really pigeonhole her,” says Clinton’s press secretary, Nick Merrill. “She was pragmatic, and wasn’t afraid to use the tools in our proverbial toolbox, as long as it was part of a larger strategy. Her approach was always that diplomacy, development and defense were only effective if used together.”

But potential 2016 opponents may not acknowledge such nuances—particularly given the way the country has grown ever-more wary of foreign entanglements. Consider the recent record:

1. Iraq Clinton paid a political price in the 2008 campaign for warning that a hasty exit from Iraq might be dangerous. But she stayed true to that view once inside Obama’s administration. As Obama began withdrawing U.S. troops from Iraq, Clinton supported an effort to leave behind several thousands soldiers for training, advisory and counter-terror missions, says James Jeffrey, who was the U.S. ambassador to Baghdad at the time. Jeffrey says Clinton sided with military officials urging a larger troop presence than the roughly 3,000 favored by some White House officials eager to bring the Iraq era to an end—including some who didn’t want to leave any troops in the country.

“Hillary Clinton was a very strong supporter of a residual troop presence and effectively backed my and the military’s views several times with others in the administration,” says Jeffrey. “At times when I felt I was being pushed around at levels below the President and Biden, she was a good person to go fix it,” Jeffrey adds. Obama wound up trying to secure an agreement with the Iraqi government for a modest residual force. But in the end, Jeffrey says, Iraqi politics would not allow for such an agreement on terms acceptable to the U.S., and no troops remained after December 2011.

2. Afghanistan After the top U.S. commander in Kabul, General Stanley McChrystal, asked Obama for another 40,000 more troops to fight the Taliban in mid-2009, several top officials—including Vice President Joe Biden—resisted, arguing in part that the public had lost patience with the conflict.

Clinton sided with the generals, and “strongly supported McChrystal’s approach,” Gates writes. He adds that Clinton actually wound up favoring slightly more surge troops than he did. Obama ultimately sent another 30,000 more American soldiers to Afghanistan. (A former Clinton State Department official says the focus on troop levels alone oversimplifies her position, which included a “civilian surge” to promote development, and the diplomatic efforts of her Afghanistan-Pakistan point man, Richard Holbrooke.)

When a White House debate later flared over when to bring the surge troops home, Clinton stood firm again. “Clinton argued forcefully that withdrawing the surge [before the end of 2012] would signal we were abandoning Afghanistan,” Gates writes. The troops departed in September 2012.

3. Libya The political grief Clinton has suffered over the September 11, 2012 attack on a U.S. compound in Benghazi, Libya, comes with an ironic twist: the tragic episode might never occurred had Clinton not supported intervening in Libya’s civil war.

Gates bridled at getting mixed up in another Arab country, insisting that vital U.S. interests were not at stake. But as Muammar Gaddafi’s forces gained momentum and threatened to massacre innocents in early 2011, influential Obama advisors, including then-U.N. Ambassador Susan Rice and national security aides Ben Rhodes and Samantha Power argued for air strikes. Even with public opinion running more than 2-1 against them, Clinton sided with the interventionists. “In the final phase of the internal debate,” Gates writes, “Hillary threw her considerable clout behind Rice, Rhodes and Power.”

That clout may have been decisive: Obama later told Gates that his decision to approve air strikes had been a 51-49 call. Had Clinton taken the other side, Obama might have, too. (For his part, Gates says he considered resigning over the issue.)

Libya is another example of Hillary’s belief in pairing diplomacy with force, says the former State Department official. “On Libya, what convinced her was being able to build a diplomatic coalition” that included the Arab League and the United Nations. “I don’t think you can separate those two things from each other.”

4. Syria Obama had no such appetite for intervening in Syria’s civil war, however, even as the country plunged into chaos in 2012. Clinton came to worry that the cost of inaction was outweighing the risk of intervention. So she teamed up with C.I.A. director David Petraeus to devise a plan to arm and train moderate rebel factions, which the two presented to Obama. The plan echoed the views of some leading Republicans, like John McCain and Lindsey Graham. But few in the White House agreed—including Obama, who rejected it.

Hillary never spoke publicly about the plan, although in June her husband urged Obama to be less cautious about Syria. “Some people say, ‘Okay, see what a big mess it is? Stay out!’ I think that’s a big mistake,” Bill Clinton said.

When Obama threatened air strikes last fall to punish the Syrian regime’s use of chemical weapons, Hillary Clinton did support him with a pair of public statements. She was apparently undaunted by polling that showed more than 70 percent of Americans opposed to military action.

5. Iran Clinton brought a hard-line background to the topic of Iran. In April 2008 she warned that the U.S. could “totally obliterate” Iran in retaliation for a nuclear attack on Israel—prompting Obama to chastise her for using “language that’s reflective of George Bush.”

In Obama administration debates about Tehran’s nuclear program, Clinton opposed talk of ‘containment,’ a policy option that plans for a world in which Iran possesses a nuclear weapon. Preparing for containment implies a decision not to use military force to prevent an Iranian bomb in the event that diplomacy fails.

“She was not a fan of containment, believing that it would not work,” says Dennis Ross, a former top Middle East policy staffer in the Obama White House.

Clinton does not share the view that diplomacy with Iran is hopeless, however. She was the first Obama official to suggest that Iran could maintain a domestic uranium enrichment program under an international nuclear deal. And one of her most trusted State Department aides, Jake Sullivan, conducted secret talks with the Iranians in Oman. “She was skeptical that diplomacy would work with the Iranians but absolutely convinced that we had to test the possibilities,” Ross adds.

6. Al Qaeda Though it looks like a no-brainer in hindsight, Obama’s national security team was not unanimous about the wisdom of the May 2011 Navy SEAL raid to kill Osama bin Laden. But while Gates and Biden opposed the operation, Clinton was for it—as she has boasted since leaving office. And while some observers wondered if the liberal background of her hand-picked State Department legal advisor, Harold Koh, might produce new restrictions on lethal drone strikes, Koh instead devised legal reasoning that supported Obama’s aggressively expanded drone campaign.

If Clinton runs for president in 2016, she’s likely to emphasize the more dovish aspects of her record—including her public diplomacy to repair America’s international image, her focus on building ties in Asia, and her attention to women’s rights and development issues.

But at a time when fewer Americans support an active U.S. role in foreign affairs, Clinton’s comfort with the harder side of American power could be a vulnerability. A liberal primary challenger might well reprise Barack Obama’s 2007 line that Hillary’s record amounts to “Bush-Cheney lite.” One potential contender, Montana Governor Brian Schweitzer, has already been zinging her over her 2002 Iraq vote. “When George Bush got a bunch of [Democrats] to vote for that war, I was just shaking my head in Montana,” he said recently. Whether such attacks will hold even a fraction of the valence they did at the Iraq war’s peak remains to be seen.

And in a scenario that would have seemed absurd in 2008, Clinton might even wind up defending her left flank against a Republican general election opponent. At a moment of rising isolationism in both parties, a GOP nominee could bash Clinton for defying public opinion on Afghanistan, Syria and Libya. Even a relative GOP centrist like Marco Rubio opposed Obama’s planned air strikes against Syria.

Such a dynamic could scramble American politics in surprising ways. In August, the New Republic asked John McCain whom he would support in a matchup between Clinton and the Kentucky Senator Rand Paul, a fulsome critic of American military interventions. “Tough choice,” McCain replied.